Feed finger for machine tools



April 29, 19-30. J. R. OCONNELL FEED FINGER FOR MACHINE TOOLS Filed April 13, 1927 I E A; E I I E 5 p,

A F 3 F A TTOR/VEYS Patented Apr. 29, 1930, i

JAM s R. oco nEL 01E, ELIVIIRA, NEW YORK, ASSIGNOR 'ro MORRISON MACHINE PRODUCTS, IEc.,. oEEL1vII A, NEW YoRK' i FEED. FINGER FOR MACHINE moons Application filed April .13,

i This invention relates to feedfingers of the kind which are used for feedingwork, such as rods or bars, on an automatic screw machine or thelike. H g s I Feed fingers as heretofore made generally consist of a piece oftubular material havingone end shaped to fit the work which is to be fed and to grip the same,.and the other end.

the feed finger being given a spring temper so'that the slotted end or'jaw of the'feed finger willyieldingly gripthe work. These feed fingers, even if very carefully made;

have ,a tendency to break at. the innermost end of the slot,since whenever the jaws of the gripping portion of the fed fingers move toward or from each other, the greatest'deflection or movement of particles of the material relatively to each other takes place' at the innermost ends of theislot, thus resulting ultimately in crystallization and'in break p elevation of a feed finger of another modified 7 construction. Y Y

ing ofthe feed finger at this point.

"t has also been attemptedto' make feed f fingers in which the slot or slots are provided elusive are each provided with an end Aof with enlargements formed in such a-manner that the deflection of the material of the. feed finger'will be distributed uniformly over a considerablelength of the feed finger. These enlargements of the slots must be of a definite curve and must be extremely accurately formed in order to insure a uniform distribution of the deflection or movement of particles of the material throughoutthe length of the enlargement, and'are consequently eX- pensive to make. Furthermore very slightvariations in the heat treatment of the feed finger, or in the composition or dimensions of the material of the feed finger results in rendering the contour or curvature of the enlargements incorrect fora paticular feed finger so that a uniform distibution of the' deflection of the material is notattained.

Theob-jects of this invention are to provide a feed .finger'of comparatively inexpensive construction in which the deflection of the material takes place at; a plurality of 1927. SeriaLNo. 183,311. 1

points ratherthan at a single point or along a definite length offlthe feed finger, sothat the tendency ofth'e's e feed fingers to crystallize and break at a'particular point is very materially reduced ,also to provide a feed fingerv with a series of substantially circular holes ar- 1 ranged lengthwise thereof for the purpose of distributing the deflection of the material of the feedlfingerj to a series of points 'correspending to the number of holes'used; also to provide a feed finger having apertureswhich are graduated to vary the tension with which the feed finger grips the work; also to improve the constructio nof feed fingers in other respects hereinafter specified.

In the accompanying drawings,

Fig. 1 is a central, longitudinal,sectionalelevation of a feed-finger embodying this invention. v

Fig. 2 is an end view thereof. ..Fig. '8 is a transverse, sectional elevation thereof on line 3,.3, Fig. 1. 7 v ,Fig. 4 is a longitudinal, sectional elevation of a feed finger of modified construction.

Fig.5 is a longitudinal, central sectional The feed fingers shown iii-Figs. 1 to 5 indesired manner to cooperate with the particular machine for which the feed finger is intended. .B represents. the work-gripping end of-the feed finger, the inner surface 6 of which is shaped to conform with the contour of the outer surface of the work which is to be fed. This end of-the feed finger is provided with the usual slot or slots C extend' ing. inwardly from this end of the feed finger, one such slot being shown in the particular constructions illustrated,'which divides the gripping end of the feed finger :into two spring jaws, but it will be understood that more slots may be employed, if desired, so that the feed finger may have three or more feedfinger is heat treated in such a manner as to produce the maximum degree of hardness, since this end of the finger is subjected to severe wear, for the reason that after the work has been advanced, the feed finger slides backwards along the work, while resiliently gripping the same, into a position to again advance the work. D represents the intermediate portlon of the feed finger which must beheat treated in such a manner as to have a spring temper tending to press the parts of the work gripping portion 13 into engageto bending than would fiat spring plates of the same cross sectionalarea and consequently when slots of uniform thickness .are used, the greaterpart ofthe deflection of the metal caused by the movement of the, gripping portionsB toward and from each other, will take place at the innermost end of the slot and consequently" cause crystallization and breaking atthese points, as has been pointed In order to relieve'the stresses and deflection in the material at the innermost end of the slot a plurality of holes are drilled in thespring tempered portion D of the feed finger at points intersecting the slot C, three such holes E being provided in the construction shown in Figs. 1 to 4:. These holes form rounded recesses in the opposite edge por-- tions of the spring jaws and can be readily formed by the ordinary drilling operation,

7 and therefore add practically nothing to the cost'of the feed fingers. These holes or recesses in the edge portions of the spring jaws,

by "reducing the cross section of the spring tempered material ofthe part- D of the feed finger, cause the deflection of the material of thefeed finger to take place atthe portions 7 of the feed finger adjacent to these holes and consequently the total deflection in'the material of the feed finger is distributed at a number ofpoints correspondingto the number of holes, thus greatly reducing thedefieo tion of the material atany part of the teed finger and thus greatly reducing the tendency of the-finger to break. Consequently in the construction shown in Figs. 1. and 4, when three holes or enlargements are used in the slot 0, the total deflection in the material of the feedfinger will take place approximately in three planes extending transversely ofthe feed finger and through the centers of the holes, the greatest defiection taking place in the plane passing through the hole farthest removed from the work gripping portion B of 'the feed finger, a lesser defiection taking placeiin the plane extending through the middle holes or enlargements, and a still smaller deflection at the hole or enlargement nearest to the gripping end B of the feed finger. If more than three holes are used a further distribution of the deflection takes place, and if only two holes are used the defiection is divided between the transverse planes passing through the two holes.

finger to yield more readily in the transverse plane extending through the holes or enlargement-s E and F. The holes F may be arranged substantially in the same transverse planes as the holes E as shown in Figs. 1 and 3, or,

if desired, they may be staggered'with refer- I ence to the holes E.

In the particular construction shown in Fig. 5 an arrangement or" holes is illustrated which tends to. equalize the deflection of the material at different points along the slot G. Since the maximum deflection of material will tend to take place at the portions of the feed finger adjacent to the innermost end of the slot if the slot is of substantially uniform width, an equalization of the distribution of the defiection'in the material can be etlected by providing a hole or enlargement of comparatively small diameter at the portion of the slot C farthest removed from the gripping portion B of the feed finger, and by making the other holes or enlargements of successively greater diameter. In the particular construction illustrated in Fig. 5 three holes or enlargements are used in the slots C, the hole G at the innermost end of. the slot being ofcomparatively small diameter, .the intermediate hole H being oi somewhat greaterdiamete'r and the hole I being the largest in diameter. By nieansof this arrangement the deflection oi the material of the feed finger in planes extending transversely through the centers of these holes can be made equal in the transverse planes extending through each of these holes, so that in the particular construction shown approximately one-third of the total detlcetion of the material takes place in each transverse plane extending through a hole. The remaining portions of the parts D of the feed finger may be imperforate, or if desired a secross section'al'area otthe feed fingerfatthes'e holesan'd thus render the parts ofthe feed finger more resilient. i It will be obvious that the same result could'be accomplished if the holes Gr, Hand I shownin Fig. 5 were madeof the same size and the'holesK,L and M successivelylarger in size as shown, since the deflection of the material in each case takes place at the reduced cross sectional area of the resilient portion D of the'feed finger, and by making the greatest reduction in cross sectional area at points nearest tothe,

gripping portion B of the feed finger, an

' equalization of the distribution of the defle'ctions of the material in the feed finger may be accomplished. "By making the'transverse holes in the spring portion D of the feed finger substantially 'circulariin cross sectionit will be obvious, that not only is the cost'of making theseholes very inexpensive because of the simplicity of the drilling operation, but also the round holes leave no sharp corners or angles in the feed finger at, which the deflection of the material may be concentrated and thus cause a rapid crystallization of the I material. Furthermore by reducingthe cross'section of the feed finger at a plurality of definite points asshown in the drawings, an inaccuracy in the heat treatment, such, for example, as would render aportion of thefintermediate parts D of the feed finger harder than is required to produce the desired spring action, would not damage the feed finger, since even if the deflection of the 1 material is entirely prevented at the hole 7 nearest-to the gripping portion B, the other two holes will still cause a distribution of the total deflection, which will result in increas- 2. A work advancingv feed finger for a machine tool having a hardened work gripping end, a spring portion adjacent thereto and located at a distance from said end and a slot extending lengthwise of the feed finger from the work gripping end through the s rin ortion thereof said slothavin a plurality of rounded enlargements located in said spring portion and which form portions ofreduced cross sectional area in the'spring is distributed the total deflection of the material in the spring'fingenlcaused by the movement bf the Work pp ng parts toward d'jfrom each other, a v

3. A; work advancingieed finge'r for machine tools having a-hardened work gripping 7 end and a spring portion adjacent thereto,

said work gripping end and spring portion being slotted to divide the same into a phi-- rality] or resilient work gripping jaws, and e' a plurality of substantially circularholes in the spring portion of said feed'fingerwhich decrease the cross section of said spring portion to distribute the deflection of-the mate'- rial due to fiexingof said spring portion to thepart's of the'feed finger adjacent to said 1 holes. 7 v

4,..A feed finger for machine tools having a hardened work gripping end and a spring portion connected therewith and located at a distance therefrom, said work gripping-and spring portions being slotted to divideithe same into a plurality of spring membersi'and said spring] portion having; a plurality of drilled holes therein at'intervals lengthwise thereof, to reducethe cross section thereof "at intervals.

'5; A workadvancing feed finger of substantially tubular form for machine tools,one

end of which feed finger is dividedinto a plur'alit'y of spring jaws having spring portions terminating in'workgripping ends, the cross sectional-area of the spring portions of said spring aws being reduced in cross sectlon at intervalsalong thelength thereof and at :a distance fro'msaid gripping endsto provide for a'distributionof defi'ection'of the material at intervals alongsaid spring portions, when the spring aws are fleXed,'to each of the'portio'ns of reduced cross se'ctionalarea.

6.,1A' work advancing feed finger of substantiallytubular form for machine tools, one end of which feed finger is divided into a pluralityof spring jaws having spring portions "terminating in work gripping ends, said spring jaws being provided at their edge portions with inwardly extending recesses and 'being'provided with orifices intermediate of the edge portions thereof and at a distance from said work gripping ends, said recesses and orifices reducing the cross sectional'area r of'said spring jawsat intervals along the length thereof todistribute the deflection of the material of said jaws, due to flexing of said aws, to said reduced cross sectional jareas.

7. A work advancing feed finger of sub: stantially tubular form for machine tools,

said finger being slotted lengthwise to divide a part of the same into a plurality of spring jaws each of which has a spring portion terminating in a work'gripping end, the material of said jaws being of reduced cross secpor ion of sald feed finger, to which portions tional area'at a number ofpoints lengthwise I thereof, said reduction-in'cross sectional area I jaw being provided with rounded recesses in the side edges thereof, said recesses being largest at the portions of the spring jaws adj acent to the work gripping ends thereof and being of gradually reduced size toward the largest holes being nearest to the work gripping end of said Spring jaw to effect further graduated reduction at intervals in cross sectional area of said spring jaws.

JAMES R, o CONNELL,

other ends of said spring jaws, to provide 7 portions of said jaws of varying reduced cross sectional area, said variation in cross sectional area serving to distribute deflections ofrthe material in said spring jaws substantially equally throughout the portions thereof of reduced cross sectional area.

9. A work advancing feed finger for machine tools including a substantially tubular body portion divided lengthwise into a plurality of spring jaws each of which includes a springport-ion terminating in a work gripping end, the spring-portion of said spring jaw being provided with rounded recesses 1n 7 the side edges thereof, said recesses being largest at the portions of the spring aws adjacent to the work gripping ends thereof and being of gradually reduced size toward the other ends of said spring jaws, to provide por: tions-of said jaws of varying reduced cross sectional area, said variation in cross sectional V area'serving to distribute deflections of the material in said spring jaws suhstantially equally throughout the portions thereof of reduced cross sectional area, and a series of holes in said jaws extending lengthwise thereof for producing a further reduction in the cross sectional area thereof.

10. A work advancing feed finger for machine tools including a substantially tubular body portion divided lengthwise into a pluralityof spring jaws each of which includes a spring portion terminating in a work gripping end, the spring portion of said spring jaw being provided with rounded recesses in the side edges thereof, said recesses being largest at the portions of the spring jaws adjacent to the work gripping ends thereof and being of gradually reduced size toward the other ends of said spring jaws, to provide portions of said jaws of varying reduced cross sectional area, said variation in cross sectional area serving to distribute deflectlons of equally throughout the portions thereof of reduced crossrsectional area, and a series of (holes in said jaws of graduated size, the

. the material in said spring jaws substantially 

